Add mypy as a dev dependency #4

	name: Mypy Type Check

	on: [push, pull_request]

	jobs:
	mypy:
	runs-on: ubuntu-latest

	steps:
	- name: Checkout code
	uses: actions/checkout@v2

	- name: Set up Python
	uses: actions/setup-python@v2
	with:
	python-version: '3.x'

	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install .[dev,test]

	- name: Run mypy
	run: mypy src tests

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